1. Field of the Invention
This invention pertains to metallic nanowire structures and methods of making the same.
2. Brief Description of Relevant Art
Nanowire structures have utility in various electronic and microelectronic applications. The unique electrical, optical, magnetic, catalytic, mechanical and tribological properties of such nanostructured materials provide numerous opportunities in a variety of applications. Various metallic compositions have been considered for integration into nanowire structures. Of particular interest are materials having characteristic properties which differ from various common metals in at least one aspect such as anisotropic Fermi surface, low carrier density, small carrier effective mass and long carrier mean free paths. Additional advantageous characteristics can include materials which exhibit very large positive magnetoresistance at room temperature. Such nanowire structures advantageously include metallic compounds which contain bismuth, tin, lead, indium, zinc, or antimony.
Heretofore, various approaches have been employed to produce metallic nanowires. Single filaments of materials such as bismuth with diameters in the micrometer range have been made using various processes such as the Taylor process. Nanowires containing materials such as bismuth having diameters as small as 200 plus nanometers have been fabricated using high pressure casting from a liquid phase. Additionally, porous alumina host media have been employed to produce metallic nanowires containing materials such as bismuth by pressure injection of molten bismuth or by infiltrating and condensing bismuth vapor into porous alumina channels. The resulting nanowire had a diameter between 10 and 200 nanometers. The resulting nanowires produced by the methods are characterized by multiple crystalline regions and essentially short finite lengths. The lengths of nanowires produced by such methods typically is one which provides an aspect ratio of length to diameter of 10 or less.
Thus, it would be desirable to produce a metallic nanowire having enhanced characteristics such as at least one of enhanced crystalline domain, elevated aspect ratio, small diameter and increased length. It is also desirable to provide a method whereby such nanowire material can be produced efficiently and economically in a highly reproducible manner.